I am trying to design the LTC4150 into a NiMH battery powered product, but am confused as to whether it will work because I have 2 different operational modes. I have my normal run mode that draws around 100mA and my low power mode where the LTC4150 will only be tracking battery current with a very light load (around 200-300uA). From reading the data sheet it says that this part wants a +/-50mV drop across the sense resistor. This is impossible to have with both operating modes. So my questions are,
1. Can this chip count charge in my low power mode if I size a resistor for the run mode. Said differently, can this part still measure a very small voltage drop across the sense resistor with my 200-300uA of current?
2. If yes to #1, what impact on accuracy does this have?
3. As for my operating mode - I have to use a fairly high resistor to get a 50mV drop across the sense resistor with 100mA. Is there a way I can bring this down? Does the part actually need a high voltage drop like ~50mV? This kind of couples with question #1.
4. Is it possible to buffer the signal with an amplifier so I can use a smaller sense resistor, use the differential amp to apply a gain that drives the sense pins of the LTC4150?